Spark plug



Sept. 15, 1953 s. I. JOHNSON SPARK PLUG Filed 0%. l, 1951 Patented Sept. 15, 1953 SPARK PLUG Stephen Ironside Johnson, Hastings, Mich., as-

signor to Hastings Manufacturing Company,

Hastings, Mich.

Application October 1, 1951, Serial No. 249,084

Claims.

This invention relates to improvements in a spark plug.

The main objects of this invention are:

First, to provide a spark plug which maintains its efficiency over a long period of time and one which can be very economically produced and in which the ground electrodes are so mounted as to be protected against erosion and accidental mechanical injury in handling.

Second, to provide a spark plug having these advantages in which the electrodes may be easily and effectively gapped in manufacture or for use in particular installations.

Third, to provide a spark plug a, unitary insulator shell and ground electrode assembly with one which may be produced very rapidly and economically and with great uniformity.

Objects relating to details and economies of the invention will appear from the description to follow. The invention is pointed out in the claims.

. A preferred embodiment of the invention is illustrated in the accompanying drawings, in which:

Fig. 1 is a fragmentary elevational view of a spark plug embodying the invention, portions being broken away and in vertical section to show structural details.

Fig. 2 is an end view of the insulator shell with the ground electrode assembly of the invention omitted.

Fig. 3 is an enlarged inner end view of the improved spark plug.

Fig. 4 is a fragmentary enlarged side elevational view partially broken away and in section on a line corresponding to line 44 of Fig. 3.

Fig. 5 is an inner end view of a modified form or embodiment of the invention.

It will be understood that in the accompanying drawing no attempt has been made to illustrate the structure embodying the invention in commercial sizes and proportions, the figures being considerably enlarged as compared to commercial structures.

In the accompanying drawing i represents the insulator having an insulated electrode 2 mounted therein. The insulated electrode is provided with a binding post portion 3 at its outer end. The details of the insulator and the mounting of the insulated electrode therein are not illustrated as such details form no part of the present invention. The insulator shell 4 is provided with external threads 5 at its inner ends adapted to be threaded into a bore provided to receive the same in the cylinder head of the engine. It

will be noted that the insulated electrode 2 projects centrally into the shell but terminates within the shell. Two ground electrodes 6 are provided in both embodiments of the invention illustrated. These electrodes are fonned of bendable stock, preferably of flat rectangular section as is illustrated.

The shell 4 has slots 1 extending axially from its inner end. In the preferred embodiment these slots are angularly spaced approximately with corresponding inner walls 8 thereof in a plane through the axial center of the shell as is clearly shown in Fig. 3. The ground electrodes are disposed in the slots against the outer walls 9 thereof and are welded to such walls and to the bottoms of the slots as indicated at It! in Fig. 4. The slots are of a substantially greater width than the electrodes so that when the electrodes are secured in position there are openings H at the inner sides of the electrodes. The slots are desirably cut so that when the electrodes are mounted against the walls 8 of each of the slots the electrodes are in parallel relation with their inner ends in overlapping laterally spaced relation and in side overlapping laterally spaced relation to the insulated electrode 2.

The openings 1 l at the inner sides of the electrodes are of such dimensions as to receive a tool such as a screw driver of suitable size, permitting the tool being fulcrummed upon the walls 8 of the slots for levering engagement with the electrodes to properly adjust the gap between them and the insulated electrode. This is not only of advantage in the manufacture but it is of advantage in use. In this connection it should be borne in mind that different engines or different makes of engines require, for the best efliciency, particular gap spacings and this permits not only proper spacing at the factory, as stated, but at the time of installing or when spark plugs are replaced or when they are cleaned. The gapping adjustment may be effected without in any wise injuring the insulated electrode.

The applicant deems it of decided advantage to have the electrodes in side overlapping relation to the insulated electrode as it not only insures efficient sparking but permits a wide range of adjustment which is not possible where the ground electrode is arranged radially of the insulated electrode. All of the electrodes are within the shell and guarded thereby against erosion and injury in handling.

Applicant is one of the applicants in the ap- ".7 plication of Dutterer, Johnson and Hein, Serial No. 107,876, filed August 1, 1949, now Patent No. 2,614,548. The present application is an adaptation of and in some respects an improvement upon the structure there illustrated.

I have not attempted to illustrate or describe other embodiments or adaptations of my invention as it is believed that this disclosure will enable those skilled in the art to embody or adapt my invention as may be desired.

Having thus described my invention what I claim as new and desire to secure by Letters Patent is:

1. A spark plug and ground electrode assembly comprising atubular insulator shell having slots extending axially from its inner end, the slots being angularly spaced approximately 180 with corresponding inner walls thereof in approximately a plane through the axial center of the shell, and a bendable ground electrode disposed in each of said slots against the outer walls thereof and welded thereto and to the bottoms of the slots, the electrodes being in parallel relation with their inner ends free and disposed in laterally spaced overlapping relation, relative to each other and to the axial center of the shell and being within and guarded by the shell, the slots being of a width substantially exceeding the thickness of the electrodes and open at the inner side of the electrodes facilitating the engagement of a tool with an electrode and fulcrumming engagement of the tool with the edge of the slot for adjustment of the electrode relative to the axial center of the shell.

2. A spark plug shell and ground electrode assembly comprising a tubular insulator shell having angularly spaced slots extending axially from its inner end, and a bendable ground electrode disposed in each of said slots against a side wall thereof and welded thereto and to the bottoms of the slots, the electrodes being within and guarded by the shell, their inner ends being free for adjustment, the slots being of a width substantially exceeding the thickness of the electrodes and open at one side thereof to receive a tool facilitating the adjustment of the electrodes within the shell.

3. A spark plug shell and ground electrode assembly comprising a tubular insulator shell having a plurality of angularly spaced slots open to and extending from its inner edge, and a bendable ground electrode disposed in each of said slots against one wall thereof and fixedly secured thereto, the slots being of a substantially greater width than the thickness of the electrodes and open at one side of the electrodes to receive a tool engaged With an electrode facilitating adjustment thereof.

4. A spark plug shell and ground electrode assembly comprising a tubular insulator shell having a slot extending axially from its inner end edge, and a bendable ground electrode disposed in said slot against one wall thereof and welded thereto and to the bottom of the slot with the inner end of the electrode free, the electrode being within and guarded by the shell, the width of the slot substantially exceeding the thickness of the electrode thereby providing a tool receiving opening to facilitate the adjustment of the electrode within the shell.

5. A spark plug and ground electrode assembly comprising a tubular insulator shell having a pair of adjacent but spaced slots extending axially from its inner end, and a pair of bendable electrodes disposed in parallel relation against the outer walls of said slots and welded thereto and to the bottoms of the slots, the electrodes being laterally spaced within and guarded by the shell, their inner ends being free for adjustment, the slots being of a width substantially exceeding the thickness of the electrodes anal open at the sides of the electrodes to receive a tool facilitating the adjustment of the electrodes with the inner walls of the slots constituting fulcrumming supports for the tool.

STEPHEN IRONSIDE JOHNSON.

References Cited in the file of this patent UNITED STATES PATENTS Number Name Date 1,156,796 Meaker Oct. 12, 1915 1,940,324 Rabezzana Dec. 19, 1933 

